Copper(I)-Catalyzed Cascade Synthesis of 2-Arylsulfanyl-arylcyanamides

We have developed a ligand-assisted copper(I)-catalyzed two sequential heteroarylation sequence. An intramolecular S-arylation is followed by an intermolecular N-arylation leading to the direct synthesis of N-aryl-2-aminobenzothiazoles. In most cases however, the 2-arylsulfanyl-arylcyanamide was the major product obtained via an intramolecular C-S bond formation, associated with C-S bond breakage, followed by an intermolecular S-arylation. The selectivity of this ligand-assisted reaction is quite different as compared to that of ligand-free reactions and the rates are much faster giving good yields of products. Various cyanamides can be prepared in excellent yields from their corresponding 1-substituted thioureas with or without the assistance of a ligand with a catalytic quantity of copper(I).